1. Field of the Invention
The present invention relates to an ink-jet printer, a head for ink-jet printer and a flexible cable usable for the same.
2. Description of the Related Art
As an ink-jet printer which performs recording on a recording medium by discharging an ink, there is an ink-jet printer which is hitherto widely known and which is provided with a cavity unit which has a plurality of nozzles, a plurality of pressure chambers communicating with the nozzles respectively, and a manifold temporarily storing an ink to be supplied to the pressure chambers; and an actuator unit which has a plurality of individual electrodes formed corresponding to the pressure chambers, respectively, and which supplies driving voltage to the individual electrodes so as to change volume of the pressure chambers corresponding to the individual electrodes, respectively, thereby discharging the ink from the nozzles.
As such an ink-jet printer, an ink-jet printer is known which has individual surface electrodes, auxiliary electrodes (land portions, adhesion land portions or weld land portions) electrically conducted to the individual surface electrodes respectively and not overlapping in a plan view with the pressure chambers respectively; and in which the auxiliary electrodes are aligned in rows in one direction to be connected to connection pads (connection terminal portions), respectively, of signal lines of a flexible cable (see, for example, FIGS. 10A to 10D of U.S. Pat. No. 7,004,565 which correspond to FIGS. 10(a) to 10(d) of Japanese Patent Application Laid-open No. 2003-311953).
In the recent years, in an ink-jet printer, there is an attempt to miniaturize the head and to highly densify the nozzles (to arrange the nozzles highly densely) in response to the demand for high-speed printing and improvement of printed image and/or letter. For this purpose, it is demanded to make the pitch of nozzles as narrow as possible. In the ink-jet head described in U.S. Pat. No. 7,004,565, however, there is a problem that in a flexible cable (FPC, COF or COP) used for connecting the individual surface electrodes of the actuator unit to a control board, signal lines (a conductive pattern formed on a flexible and insulative substrate), connected to the land portions corresponding to the individual surface electrodes, respectively, are concentrated (congested) on a side of the flexible cable at which the signal lines are drawn, thereby increasing the number of signal lines on this side of the flexible cable. Accordingly, the wiring (line) pitch of the signal lines (conductive pattern) becomes narrow and thus it is difficult to realize a miniaturized head and densified nozzles (nozzles which are arranged highly densely).
Further, there is also known an individual surface electrode having a driving portion overlapping in a plan view with a pressure chamber and a land portion conducted to the drive portion and not overlapping in a plan view with the pressure chamber (see, for example, FIG. 1 of Japanese Patent Application Laid-open No. 2004-328973).
Even if providing such a land portion, however, the wiring pitch of the signal lines in the flexible cable is still narrow.
Furthermore, there has been proposed a wiring structure in which head terminals, arranged on and conducted to surface electrodes, respectively, of the ink-jet head, are arranged in a staggered manner, thereby arranging terminal electrodes, which are connected to the head terminals respectively, also in a staggered manner (see, for example, FIG. 4 of U.S. Patent Application Publication No. US 2004/0060969 A1 corresponding to FIG. 4 of Japanese Patent Application Laid-open No. 2004-114609).
However, even when the head terminals of the surface electrodes and the terminal electrodes of the flexible cable in the ink-jet head are formed in a staggered manner, as in the wiring construction described in U.S. Patent Application Publication No. US 2004/0060969 A1, the sizes of the head terminals and terminal electrodes cannot be reduced substantially for the following reason. That is, when electrically connecting the head terminals to the terminal electrodes by soldering, it is necessary to ensure the electrical connection between the head terminals and the terminal electrodes. However, when the sizes of the head terminals and the terminal electrodes are reduced to be small, there is a fear that the electrical connection cannot be performed successfully if the head terminals and/or the terminal electrodes are deviated from (moved out of) their positions even by a small amount while performing the connection. Therefore, in such a wiring construction, the pitch of the signal lines of the flexible cable is still narrow, which in turn makes it difficult to further arrange the nozzles highly densely.
In order to advance the further densification of the nozzles and to increase the number of the individual surface electrodes, it is necessary to use a plurality of flexible cables (for example, FPC or COP). However, the increase in the number of flexible cables not only weakens the mechanical strength of the wiring connection considerably but also increase the production cost.